[1]} validate that asking clarifying questions is of significance in IR by performing a large scale user study, where a group of users are asked to use the Web search engine with an interface of using clarifying questions, as shown in Figure REF . The study concludes that “users enjoy seeing clarifying questions, not only because of their functional benefits, but also due to their emotional benefits.” In other words, a CIR system that asks clarifying questions looks more intelligent, and is easier to win users' trust.
